1. Field of the Invention
This dual purpose invention pertains to a subterranean drainage system for draining water away from basement foundation walls and to assist in venting radon gas that may be present in soils adjacent to basement walls. The invention may also be used as a trench drain.
2. Prior Art
The conventional basement drainage system is a sand or gravel covered pipe drain. For a trench drain, the conventional drainage system requires digging a trench, inserting a drainage pipe into the trench and covering the pipe with either sand or gravel or both and backfilling with soil if necessary. Such a conventional drainage system can also be used against below grade structural foundations.
U.S. Pat. No. 4,490,072 to Glasser discloses a subterranean drainage device utilizing a core made of a stiff plastic sheet having rigid raised portions and alternate valleys. Wrapped around the core is an envelope of non-woven material sealed at its top and bottom. Sufficient space is provided in the bottom of the envelope to allow for the insertion of a drainage pipe having raised annular portions. When the pipe is in place within the envelope the raised annular portions contact the core. The envelope being sealed along its bottom before installation of the drain pipe makes installation more difficult and expensive. Long sections of pipe must be inserted through the envelope making installation more tedious and time consuming.
The patent to Healy et al., U.S. Pat. No. 3,654,765, discloses a subterranean wall drain including a continuous expanded plastic core. Pervious sheet material is bound to one side of the core and a plastic sheet or other vapor barrier forming material is bound to the opposite side of the core. In one embodiment the core and drainage pipe are formed of a single continuous sheet. In another embodiment the core is inserted into the drain pipe through a longitudinal slot in the pipe.
These drainage systems typically cover the entire wall surface of a below grade foundation using more material than is necessary to accomplish the task and are difficult to install. No known system accomplishes all of the objectives of the present invention with as little expense or its ease of installment.